First, I'm sorry to hear about the loss of your dog. We just lost our 11 1/2 year old Akita, Tunaka last Monday. Much like you, I did everything in my power to assist him over the past several months as his health deteriorated. The days leading up to having to take him to the vet and several days after were simply devastating. Even though I knew he was sick I didn't think I was going to be normal ever again after having had to put him to sleep.
Again, much like you, I needed to find some sort of happy memory to help me through the grieving process. Although I miss him dearly, I haven't cried about losing him in three days. Until today that is. Today we received several sympathy cards in the mail from friends. It brought back a rush of emotion and loss.
The grieving process is strange and it effects everyone differently. Rather than worry about what the grieving process for you looks like compared to what it might look like for others, revel in the fact that you had a special relationship with your dog. As I'm finding out, some days I feel at total peace with Tunaka not suffering anymore and our decision to have him put to sleep. Other moments I miss him desparately.